Power steering booster of the



P 14, 1954 R. A. GARRISON Re. 23,867

POWER STEERING BOOSTER or THE HYDRAULIC TYPE Original Filed Dec. 22,1949 4 Sheets-Sheet 1 IN VE N 70/? ROBERT A. CARR/SON AT T OR/VE VS 4Sheets-Sheet 2 R. A. GARRISON POWER STEERING BOOSTER OF THE HYDRAULICTYPE Sept. 14, 1954 Original Filed Dec.

p 14, 1954 R. A. GARRISON POWER STEERING BOOSTER OF THE HYDRAULIC TYPE 4Sheets-Sheet 3 Original Filed Dec. 22. 1949 lNVEN TOR ROBERT A. MFR/SONA TT'ORNEYS 14, i954 R. A. GARRISON POWER STEERING BOOSTER OF THEHYDRAULIC TYPE 4 Sheets-Sheet 4 Original Filed Dec. 22. 1949 B Mq'MReiuued Sept. 14, 1954 POWER STEERING BOOSTER OF THE HYDRAULIC TYPERobert A. Garrison, San Marino, Calif. Original No. 2,608,263, datedAugust 26, 1952, Se-

rial No. 134,490, December 22, 1949.

Application for reissue April 29, 1954, Serial No. 426,626

18 Claims.

Matter enclosed in heavy brackets [1 appears in the original patent butforms no part of this reissue specification; matter printed in italicsindicates the additions made by reissue.

1 This invention relates to power steering boosters for self-propelledvehicles and more specifically contemplates apparatus actuated bymanually operable valvular mechanisms by which hydraulic power isutilized for directional control of the vehicle. Hydraulic steeringboosters of the prior art adapted for actuation and control by thesteering wheel of a vehicle comprise generally a fluid motor usuallyconsisting of a piston-cylinder assembly actuated by hydraulic fluid,the flow of which is controlled by valve mechanism connected with thesteering wheel of the vehicle. In accordance with such priorconstructions, the motor and valve control are integrally connected andadapted for installation either in the drag link or at the base of thesteering shaft. As a result road shocks are transmitted through thesteering linkage before absorption by the power cylinder and pistonassembly, and in constructions wherein the fluid motor and valve areintegral, such shock places excessive stress upon the valve elements,steering gear housing or frame mountings.

While it is highly desirable that the resistance presented by theroadbed to the wheels or other steered parts in maintaining any desiredpreadJustments or in effecting directional change, should be transmittedin part to the steering wheel of the vehicle in order to facilitateresponse by the driver to varying road conditions, the actualtransmission of such resistance either in whole orin part through thesteering linkage is conducive to mechanical failures.

It is, therefore, a principal object of the present invention to providea hydraulic steering booster adapted for utility and application tomotor graders, truck, truck cranes, wheel-type tractors, or the like,comprising essentially a double acting hydraulic cylinder adapted fordirect connection to the steered wheels or other parts of the vehicleand supplied with hydraulic power controlled by valve mechanismassembled in the drag link, whereby the valve assembly is in proximateassociation with its manually operable motivating force and the power ofthe system is applied directly to the work.

More specifically, an object is to provide a fourway valve connected toa source of fluid under pressure and to a reservoir tank for thecontinuous circulation therethrough of the fluid, in combination withmeans for diverting the flow into, selectively, either end of a powercylinder to actuate the piston therein, the cylinder being normally inopen communication with the circulating system whereby the normal casterof the steered wheels is permitted to return the latter to forward,intermediate alignment and to correspondingly reposition the piston forsubsequent activation.

Another and highly important object is the provision of dual means forreturning the valve to a neutral or inoperative position, comprisingessentially normally balanced resilient elements arranged in oppositionto one another, the balance of which is upset incident to operativeadjustment of the valve, and fluid pressure elements actuated by thehydraulic circulating system, each of the two components of thecomposite mechanism being individually and jointly operable to produce apre-determined measure of resistance to manual adjustment of the valve.

Still another and related object is the provision of a telescopiccontrol valve comprising a pair of pressure actuated rings operable tonormally bear against the complementary ends, respectively, of thetelescopically related valve elements in response to pressure of thehydraulic system, relative longitudinal movement between the valveelements being effective to concentrate the pressure of the rings uponthe extended ends of the individual elements, so as to utilize thepressure of the system for returning the valve to a neutral or normalposition and induce a resistance against manual adjustment of the valveproportionate to the resistance of the load.

Numerous other objects and salient features of my invention such, forexample, as relative economy of manufacture, ease of installation,simplicity of construction and adaptabiilty and application to numeroustypes of mobile units, will be apparent to those of skill in the artupon an examination of the following description read in the light ofthe accompanying drawings, in which:

Fig. l is a perspective view of a preferred embodiment of my invention,illustrating a typical installation;

Fig. 2 is a longitudinal section through the control valve assemblyshowing the elements of the valve in neutral positions;

Fig. 3 is a fragmentary longitudinal section taken in a different planefrom that of Fig. 1 illustrating the outlet passage formed in the valvecage;

Fig. 4 is a longitudinal section through the control valve depicting thevalve elements in an extreme position in response to the thrust of anactuating force applied to the direction of the arrow;

Fig. 5 is a longitudinal sectional view through the control valvepresenting the parts in their relative positions which are assumed as aresult -of a tubular valve casing 26.

of the application of an actuating force in a direction opposite fromthat depicted in Fig. 4.

Referring more particularly to the drawings, wherein like numeralsindicate similar parts throughout the several views, it will beappreciated that the particular installation of themvention hereincontemplated and depicted in Fig. 1 is only illustrative of oneapplication of a preferred embodiment hereof. In accordancetherewith,and with particular reference to Fig. 1, my invention contemplatesessentially a hydraulic telescopic valve l adapted for interposition ina composite drag link I8 of the vehicle for controlling the flow orhydraulic fluid to a double acting power cylinder-piston assemblygenerally indicated at II and connected between the axle I2 of thevehicle and a tie rod I3. The valve I3 is actuated and controlledincident to longitudinal movement of the drag link, which movement isimparted thereto by a pitman arm I3 connected to the steering shaft I5of the vehicle by a lateral shaft I6 through conventional worm reductiongearing generally indicated at I1. Rotation of the steering wheel (notshown) of the vehicle thus swings the pitman arm I4 arcuately forward orbackward depending upon the direction of rotation of the wheel inaccordance with conventional construction and operation. The rear end ofthe drag link [3 is connected to the pitman arm I4 by a ball and socketjoint indicated in Fig. 1 at l9. Correspondingl the forward end of thedrag link I8 is connected to the steered parts of the vehicle by theusual linkage which includes a steering arm 20 and the tie rod I3,above-referred to.

A closed hydraulic circulating system is provided for supplying power tothe cylinder-piston assembly II, and includes a pump 2|, preferablydriven by the engine of the vehicle. The fluid is drawn by the pump 2|from a reservoir tank 22, suitably mounted in the chassis or thevehicle. With the control valve I3 in neutral position, later described,the pump 2| is effective to continuously circulate fluid through thevalve and thence return the fluid to the tank 22. actuated in responseto manual operation of the steering element of the vehicle, the valveII) is operatable to divert hydraulic fluid under the pressure of thepump 2| into the power cylinder assembly I I so as to correspondinglyand directly re-position the steered parts of the vehicle.

The composite drag link I3 and control valve l3 assembly comprises adrag link section 23 carrying at its rearward end the socket 24 of thejoint I9, accommodating the ball (not shown) of the pitman arm I4. Theforward end of the link section 23 is encircled by a collar 25, weldedor otherwise secured thereto. The collar is threadedly engaged with oneend of the bore The opposite or forward end of the casing 26 receives asocket sleeve 21 having a lateral opening 28 therein for projection ofthe ball 29 with which the steering arm 23 is equipped. As will appear,the steering arm 23 and ball 29 are permitted a limited range ofmovement relative to the pitman arm l4. I

Within the casing 26 and abutting the collar 25 and sleeve 21,respectively, are a pair of annular valve heads 33. and 3|, securedrigidly to opposite ends, respectively, of an intermediate valve cage 32by screws 33. Thus, the cage 32 is held rigidly with respect to thecasing 26, sleeve 21 and link section 23 and moved longitudinallytherewith in response to motivation by the pit- When i man arm l4.Similarly clamped between the valve heads 33 and 3| and within the boreof the cage 32 is a ported valve sleeve 34.

Four beveled openings 35, formed in the casing 26 permit extension of acorresponding number of hoses 36, 31, 33 and 39which are threadedlyattached in complementary openings 43 of the valve 'cage 32. Two of thehoses 36 and 31 are connected to the pump 2| and reservoir 22,respectively, through a bulkhead 4|. The other two hoses 33 and 39 areconnected through the bulkhead 4| with opposite ends of a cylinder 42forming a part of the assembly II. The cylinder 42 is pivotally mountedas at 43 to the axle of the vehicle and incorporates a piston 44(indicated in dotted lines in Fig. l). The piston rod 44a is in turnconnected by a ball and socket joint 45 to the tie rod I3. It will beappreciated that the introduction of fluid pressure through the hose 33into the mounted end of the cylinder, with a corresponding relief ofpressure in the hose 39, is effective to extend the piston rod and toshift the tie rod, turning the steered parts to the left as seen inFig. 1. Conversely, the relief of pressure in the hose 33 andcomplementary increase of pressure in the hose 39 is effective toreverse the direction of movement of the steered parts. The hoses 35,31, 33 and 39 are in open communication through the threaded openings 40with transversely aligned annular recesses 46, 41, 43 and 49 formed inthe bore of the cage. Also formed in the body of the cage 32 is an inletpassa e 50, extending longitudinally therethrough, which communicatesthe annular inlet recess 46 to an annular recess 5| disposed in the bodyof the cage 32 between the recesses 43 and 49 with which the hoses 33and 39 are connected. The annular outlet recess 41, connected with theoutlet hose 31, is similarly communicated with another annular recess 52in the forward end of the bore of the valve cage 32, by an outletpassage 32 formed in the body of the cage for a purpose later described(Fig. 3). Ports 93 in the sleeve register with the recess 52 so as tocommunicate the bore of the sleeve adjacent ports 83 with the outletpassage 82. Within the bore of the valve sleeve 34 is a relativelyreciprocable valve plunger 53, the rearward closed end of which projectsslidably into the bore of the adjacent valve head 33 and is sealedtherewith throughout the range of relative movement by a ring seal 54.The opposite end of valve plunger 53 is threaded for attachment to theend of a rod 55 which seals the corresponding end of the bore of plunger53 and projects forwardly through the hub 56 of a ball socket housing51, relative to which the rod 55 is very slightly telescopicallyextensible and contractible. A nut 53, threaded on the end of the rod 55within the bore of the housing 51 limits extension of these parts. Theball socket housing 51 is provided with a lateral opening 59complementary to the opening 23 in the socket sleeve 21 so as to receivethe steering arm 23. Encircling the hub 56 of the socket housing 51 andthe rod 55 is a spring seat 63 having an inner annular flange 6| at oneend which is loosely confined between the body of the socket housing 51and a nut 62 threaded on the hub 56. 63 indicates a set screw threadedinto the joint between the nut 62 and hub 56 of the socket housing. Ahelical spring 64 interposed between the spring seat 63 and sockethousing 51 maintains the spring seat in contact with the adjacent valvehead 3| and the nut 58 in contact with the socket housing 51.

At the opposite end of the socket housing (Fig. 5) the sleeve 21encloses a second spring seat 85 and a plug 65 threaded into the end ofthe sleeve. The spring seat 65 slidably encircles a threaded axial boss51 integral with the plug with which an inner annular flange 59 of theseat 85 is in slidable association. The flange 98 is loosely confinedbetween a nut 59 and the body of the plug 85. A spring HI, identical tothe spring 64 encircles the spring seat 65 so as to exert an expansiveurge against the plug 65 and urges the spring seat 85 against theadjacent end of the socket housing 51 in opposition to the urge of thespring 84. It will thus be observed that while the socket housing isslightly movable longitudinally relative to the sleeve 21 the springs 94and 10, being of equal strength normally tend to maintain a neutralposition of these parts. However, as the range of such movement isextremely limited, the springs are never fully compressed.

The socket housing 51 encloses a pair of socket elements H and 12adapted for reception therebetween of the ball 29 of the steering arm 20comprising a part of the linkage by which the steered parts are normallyactuated. One element II is threaded in the end of the socket housing51. A helical spring 13 enclosed by a collar 14, fitted in the bore ofthe socket housing 51 between the base of the latter and the othersocket element 12 bears against the back of the last-named element so asto resiliently confine the ball 29 of the steering arm. I5 indicates agrease fitting by which the socket assembly may be lubricated.

The valve plunger 53 is formed with a pair of annular enlargementscomprising valves 18 and 11, the former controlling flow through twoseries oi ports 18 and I9 in the valve sleeve 34 registering with theannular recess 48 communicated with the power hose 38, and the secondvalve 11 correspondingly controlling flow through two series of ports 80and 8| in the valve sleeve 34 registering with the annular recess 49communicated with the hose 39. Hydraulic fluid introduced into thecontrol valve I through the hose 36 flows through the passage 50 andrecess and enters the bore of the valve sleeve 34 through ports 83located between the annular valves 16 and 11 of the plunger 53. Therespective valve enlargements 16 and 11 are slidable with the bore ofthe valve sleeve 34 and are adapted in response to limited longitudinalrelative movement between the valve elements to close and opensimultaneously one or the other of a series of ports communicated withthe respective annular recesses 48 and 49, as will appear. The annularvalves and 11 are of a length and are spaced apart on the plunger 2.distance proportioned with the spacing of the ports l8, I9, 90 and 8|communicating with the respective hoses 38 and 39 leading to the powercylinder, whereby the valves are normally positioned between therespective pairs of ports which they control. Relative longitudinalmovement between the plunger 53 and valve sleeve 34 results in closureof ports I8 and 89 or ports 13 and 9| and the coincident opening of thecomplementary ports controlled by each valve;

With the valve II) in neutral position, the return flow of fluid fromthe valve sleeve 34 to the reservoir 22 is permitted through ports 18and 19 in the sleeve 34 registering with the annular recess 48 andthrough the second series of ports 89 and 8| in the sleeve registeringwith the annular recess 49 with which the end of the passsage 82 is incommunication. Fluid flowing through the ports I8 and 19 is thendirected into the bore of the sleeve to the outlet hose 31 through aseries of ports 94 formed in the sleeve registering with the recess 41.Fluid flowing through the ports 8l-8|l is then directed through the port93 and thence through the outlet passage 82 to the recess 41 for returnto the reservoir tank.

Each end of the valve sleeve 34 is diametrically enlarged to accommodatepressure slip rings 84 and 85, slidably fitted between the plunger andsleeve. The plunger is formed with a pair of annular enlargements 8G and81 at opposite ends and with the valve in neutral position as seen inFig. 2 are flush with the shoulders 88 and 89, respectively, formed bythe diametric enlargement of the ends of the sleeve, whereby the ring ateach end of the valve is normally adapted to contact both the adjacentenlargement and the shoulder. Pressure fluid is admitted behind therings so as to normally urge the rings against the shoulders 88 and 89of the plunger 53 or the enlargements and 81 or both, depending upon therelative longitudinal positions of the valve sleeve and plunger. To thisend, the plunger is formed with ports 90 which are in alignment with theports 83 and recess 5| terminating at the end of the inlet passage 5|].Adjacent each of the ends of the valve plunger 53 are a series of ports9| through which fluid is permitted to flow from the bore of the plungerinto the annular chambers 92 in back of the respective slip rings. Itwill be appreciated that the ports 9| are in open communication with thebore of the valve plunger 53 throughout the range of relative movementbetween the plunger and sleeve and accordingly, the rings 84 and 85 are,at all times, forced in response to the variable pressure of the pump2|, against either the adjacent shoulders 8889 of the sleeve or theenlargements 8881 of the valve plunger, or against both the shouldersand enlargements when the valve is in neutral position. Any relativelongitudinal displacement of the valve plunger 53 and sleeve 34 fromtheir neutral relationship, wherein the enlargement and shoulder at eachend of these respective parts are in flush relationship, causes the ringat one end of the plunger to bear against the shoulder andsimultaneously pressure is relieved upon the shoulder at the oppositeend of the unit. Thus, while the equal pressure of the rings 84 and 85against the respective components of the valve normally tend to opposeand thereby counteract one another, any disturbance of the normalrelationship of these valve parts sets up a counteracting force which isvariable depending upon the pressure required of the pump in theoperation of the unit, tending to return the valve to its neutralposition.

The utility and operation of the device is further briefly described asfollows: With the pump 2| driven by the engine, fluid will becontinuously circulated through the control valve l0 while the engine isrunning and will maintain a minimum equal pressure within the powercylinder 42 at opposite sides of the piston 44. In accordance with thisoperation, fluid is directed into the control unit through the hose 38case:

7 and corresponding opening 48 in the tubular valve cage 32. The fluidthence passes through the inlet passage 50 through port 88 and into thebore of the sleeve 84 between the valve enlargements l6 and 11 of theplunger 53. The fluid under the pressure of the pump 2| thus fills thebore of the valve plunger and the chambers 82 in. back of the respectivepressure rings 84 and 88. As above indicated, the rings thuscontinuously function to urge the valve sleeve 44 and plunger 53 into aneutral relationship wherein the shoulders 88 and 89 of the sleeve areflush with the complementary surfaces of the enlargements 8i and 81 atthe end of the plunger 88. In such neutral position of the valve, aswill obtain when no tortional stress is applied to either the steeringor the steered parts of the vehicle, the valves 16 and I1 are disposedintermediate the ports 'i8|8 and 8tl8| which they control, respectively.Thus the opposite ends of the power cylinder 42 are in opencommunication through the hoses 88 and 88 with the bore of the valve sleeve 84between the valves 18 and 11 and the pressure within the cylinder atopposite sides of the piston 44 therein is equally maintained. With thevalve In in its neutral position, as described, the fluid circulatesthrough the series of ports 18 and 8| into the annular recesses 48 and49 and thence returns to the bore of the sleeve 84 through the adjacentseries of ports 19 and 80. Fluid flowing through the ports '88 entersthe output passage 82 through the ports 83 in the sleeve 34 and thencereturns to the reservoir through hose '38. Correspondingly, fluidreturning to the bore of the sleeve 84 through ports 19 flows throughthe port 84 in the sleeve into hose 88 and thence to the reservoir.

Should the driver desire to change the direction of movement of thevehicle, the steering wheel is turned in a conventional manner whichis-operable to swing the pitman arm l4 in one direction or the other.If, for example, the steering wheel is turned in a counter-clockwisedirection the arm I4 is swung forwardly so as to correspondingly advancethe drag link section 28 (see Fig. 4). This movement is transmittedthrough the valve cage 82 and valve head 8| to the spring 84 interposedbetween the seat 80 and socket housing 51. Corresponding forwardmovement of the socket housing is resisted by the friction of thesteered wheels with the roadbed and accordingly, the spring 84 iscompressed very slightly bringing the spring seat 88 into abuttingrelationship with the socket housing, as indicated in Fig. [l] 4. Thevalve plunger 53 is momentarily held stationary while the valve sleeve84 is shifted forwardly with the drag link section 23. The port 19 andport 8| are thereby closed while the ports 18 and 88, normally partiallyrestricted, by the respective valves II and I1 are opened more fully.Pressure fluid is thus diverted from the ports 8| and is directed intothe hose 38 leading to the mounted end of the power cylinder 42.coincidentally, pressure at the opposite side of the piston 44 isrelieved through the hose 3!, ports 80, port 83 and the outlet passage82 connected to the reservoir 22 .by the hose 31. The piston 44 is thusadvanced so as to mechanically impel the turning of the steered wheels,directing the vehicle to the left, in conformance with the direction ofmanual actuation of the steering wheel.

The adjustment of the control valve In incident to clockwise motion oftheisteering wheel opening 40 in the valve [cake] cage 82, through ports8| and the hose 39 and into [the mounted] one end of the power cylinder42 while pressure is relieved from theopposite side of the piston 44through the hose is, thereby turning the steered wheels-to the right.

It will be noted that in the event of a failure of the hydraulic systemthe steered parts may be actuated manually in the usual manner. Theslight telescopic contraction or extension of the drag link mechanismessential to the actuation of the control valve Ill, being unnoticeableto the driver and resulting in no material delay in effectingtransmission of the movement of the steering wheel to the steeredelements.

In accordance with the operation of the control unit as above-described,the steered parts will continue to turn in the direction impelled by thepiston-cylinder assembly as long as suflicient torque is applied to thesteering wheel to maintain the valve plunger 83 in an out-ofneutralrelationship with the valve sleeve 84. However, as the hydraulic poweris applied, the piston 44 of the power cylinder again extends orcontracts the drag link in opposition to the initial urge in the pitmanarm I4 and thus promptly returns all parts of the valve to neutralpositions.

Accordingly, with the opposite ends of the cylinder 42 in opencommunication with the reservoir tank 22 the natural caster of thesteered wheels will induce the wheels to again assume a forward,straight-line relationship with the vehicle as the steering wheel isreturned to its normal position, without the application of hydraulicpower.

An important feature of the present invention resides in the backpressure created in the control valve and applied to the pitman arm I4by the pressure rings 84 and 85 which transmit to the steering wheel aresistance to turning which is less than, but at all times roportionateto, the resistance to directional variation encountered by the vehiclewheels. This proportionate resistance may thus be felt by the driverthrough the steering wheel so as to facilitate a more prompt response tohis own requirements and thereby facilitate better handling of thevehicle without imposing any strain upon the driver greater than thatrequired to operate the control valve.

It will be appreciated that'while I have shown a preferred embodiment ofmy invention, numerous changes in size, design, shape, number andproportion of the various arts may be made, and more specifically thatthe slip rings 84 and 85 may be increased or decreased in size topresent a correspondingly greater or lesser crosssectional area to thepressure of the pump and thereby modify the magnitude of the resistanceto activation of the control unit in proportion to the resistance toturning of the steered elements, that the power cylinder may beconnected to any of the linkage intermediate the drag link and wheels ordirectly to a steered part. and that any means may be substituted forthe steering wheel-pitman arm assembly to effect the longitudinalmovement of the drag link which is essential to the operation of thevalve mechanismall without departing from the spirit of my invention asdefined by the appended claims.

What I claim and desire to secure by Letters Patent is:

1. In a steering booster tor a vehicle having a steered part, steeringmeans connected to said steered part, a fluid motor comprising a pistonand cylinder, means to connect said motor to the [steered part] steeringmeans to actuate the [latter] steered part, a source of fluid underpressure, means of communication between said source of fluid underpressure and said fluid motor, a control valve interposed in said meansof communication comprising a pair of telescopically-related elementsoperable in response to relative telescopic movement from relativeneutral positions to vary the flow of fluid from said source to saidmotor, manually operable means to actuate said control valve, saidmanually operable means including a manually swingable pitman arm, amember movable with one of said valve elements and pivotally connectedto said pitman arm at a pivot point thereon, and a member movable withthe other of said valve elements and pivotally connected to saidsteering means at a pivot point thereon, and means to direct andtransmit fluid pressure from said source against at least one of saidelements of said valve in a direction to resist telescopic displacementof the same from said relative neutral positions and to oppose anychange in the dis- :Lance between said pivot points.

2. In a steering booster for a vehicle having a steered part, a fluidmotor comprising a piston and a cylinder, means to connect said motor tothe steered part to actuate the latter, a source of fluid underpressure, means of communication between said source of fluid underpressure and said fluid motor, a control valve interposed in said meansof communication comprising ,a: pair of telescopically-related elementsoperable in response to relative telescopic movement to control the flowof fluid from said source to said motor, means to actuate said controlvalve, and means comprising a ring forming a part of said valve totransmit fluid pressure from said source against complementary surfacesof said valve elements to resist telescopic displacement of saidelements from predetermined relative positions of the latter incident toactivation of said actuating means.

3. In a steering booster for a vehicle having a steered part, steeringmeans connected to said steered part, a fluid motor comprising a pistonand a cylinder, means to connect said motor to the [steered part]steering means to actuate the [latter] steered part, a source of fluidunder pressure, means of communication between said source of fluidunder pressure and said fluid motor, a control valve interposed in saidmeans of communication comprising a pair of telescopically-relatedelements operable in response to relative telescopic movement to controlthe flow of fluid from said source to said motor, manually operablemeans to actuate said control valve, said manually operable meansincluding a manually swingable pitman arm, a member movable with one ofsaid valve elements and pivotally connected to said pitman arms at apivot point thereon, and a member movable with the other of said valveelements and pivotally connected to said steering means at a pivot pointthereon, said valve elements having a air of shoulders flush with oneanother when said valve is in a telescopically neutral, inoperativeposition, and means actuated by fluid pressure from said source to bearagainst said shoulders [with equal pressure] to resist longitudinaldisplacement of said elements with respect to one another and 10 tooppose any change in the distance between said pivot points.

4. In a steering booster for a vehicle having a steered part, a fluidmotor comprising a piston and a cylinder, means to-connectsaid motor tothe steered part to actuate the latter, a source of fluid underpressure, means of communication between said source of fluid underpressure and said fluid motor, a control valve interposed in said meansof communication comprising a pair of telescopically-related elementsoperable in response to relative telescopic movement to control the flowof fluid from said source to said motor, means to actuate said controlvalve, said valve elements forming a pair of annular shoulders disposedin offset relation when said valve is in a telescopically operativeposition, a slip ring encircling one of said elements to bear againstone of said shoulders to urge said valve elements toward a neutralposition in which said shoulders are flush with one another.

5. A booster for a vehicle having a steering arm-steered part assemblyand manually actuated pitman arm, a fluid motor connected to saidassembly to actuate said steered part, pump mechanism to supply pressureto said fluid motor to actuate the same in accordance withcorrespondingly varying load requirements, means of communicationbetween said pump mechanism and said fluid motor, a drag link connectedbetween said pitman arm and said first-named assembly, a control valveforming a part of said drag link and comprising a pair oftelescopicallyrelated valve elements for controlling the flow betweensaid pump mechanism and said motor in response to telescopic adjustmentof said elements, and means to resist telescopic adjustment of saidvalve elements, actuated in response to fluid pressure from said[source] pump mechanism proportionate to but less than the pressurerequired to actuate said motor.

6. In a steering booster for a vehicle comprising a pair of steeredparts connected by a tie rod actuated by a steering arm, a fluid motorcomprising a cylinder and a piston connected to said tie rod to actuatesaid steered parts, a source of fluid under pressure, means ofcommunication between said source of pressure and said fluid motor,means comprising a drag link connected to said steering arm to actuatethe same, said drag link comprising a pair of telescopically relatedvalve elements forming a valve interposed in, and operable to controlthe flow through, said means of communication, resilient means forming apart of said valve to urge said valve elements toward neutral positions,and means actuated by fluid pressure from said source to exert avariable force in urging said valve elements toward neutral positions.

7. In a steering booster having a steered part and a manually operabledrag link, a fluid motor comprising a piston and cylinder, means toconnect said motor to said steered part to actuate the latter, a pump tosupply fluid under pressure, means of communication between said pumpand said fluid motor, a control valve comprising a pair oftelescopically-related valve elements carried by said drag link, saidvalve being interposed in said means of communication to control theflow of said pressure fluid to said motor incident to telescopicadjustment of said valve elements, a ring encircling one of said valveelements and normally bearing against each of said valve elements, andmeans to direct pressure of said pump against said ring whereby thelatter is operable to produce a resistance to telescopic actuation ofsaid valve proportionate to the load imposed upon said motor.

8. In a steerining booster having a steered part and a manually operabledrag link, a fluid motor comprising a piston and cylinder, means toconnect said motor to said steered part to actuate the latter, a pump tosupply fluid under pressure, means of communication between said pumpand said fluid motor, a control valve comprising a pair oftelescopically-related valve elements carried by said drag link, saidvalve being interposed in said means 01' communication'to control theflow 01' said pressure fluid to said motor incident to telescopicadjustment or said valve elements, a ring encircling one of said valveelements and normally bearing against each of said valve elements, meansto direct pressure of said pump against said ring whereby the latter isoperable to produce a resistance to telescopic actuation of said valveproportionate to the load imposed upon said motor,and resilient means toresist telescopic displacement of said valve elements from apredetermined relationship.

9. In a steering booster for a vehicle comprising a pair of steeredparts connected by'a tie rod actuated by a steering arm, a fluid motorcom: prising a cylinder and a piston connected to said tie rod toactuate said steered parts, a source of fluid under pressure, means 01'communication between said source of pressure and said fluid motor,means comprising a drag link connected to said steering arm to actuatethe same, said drag link including a pair 01' telescopically-relatedvalve elements comprising a valve interposed in. and operable to controlthe flow through, said means of communication, and means actuated byfluid pressure from said source to exert a force operable to move saidvalve elements toward relative neutral positions.

10. .4 steering booster as defined in claim 1 wherein said means todirect and transmit fluid pressure includes biasing means havingoperative connections to said valve elements for urging said valveelements in opposite directions toward said relative neutral positionsthereof.

11. A steering booster as defined in claim wherein said operativeconnections of said biasing means to said valve elements comprise directmechanical engagement of said biasing means with said valve elements.

12. In a steering booster for a vehicle havin a steered part, steeringmeans connected to sa d steered part, and a pitman arm, the combinationof: an extensible and contractible structure operatively interconnectingsaid pitman arm and said steering means, said structure includingmembers slidable relative to each other and connected. respectively, tosaid pitman arm and said steering means at predetermined points thereon;a hydraulic motor connected to said steering means and to a fixed partof said vehicle to actuate said steered part; a source of fluid underpressure; a control valve interposed between and connected to said motorand said source and including a pair of telescopically related elementsrelatively movable in opposite directions from a neutral position tocontrol the operation of said motor, said valve elements being connectedto said members, respectively, to be moved thereby relative to saidneutral position in response to any change in the distance between saidpoints; and hydraulic means supplied with fluid from said source andacting on said members for opposin any change in the distance betweensaid points.

13. A steering booster as defined in claim 12 wherein said motor extendstransversely of said vehicle and includes relatively movable cylinderand piston members one connected to said steering means and the other tosaid jlmed part of said vehicle.

14. In a power steering apparatus for a vehicle having a steered part,steering means connected to said steered part for steering same, and asteering-wheel-operated pitman arm, the combination of: a source ofhydraulic fluid under pressure; a hydraulic motor operatively connectedto said steering means; a link having connections to said pitman arm andsaid steering means, said link including two structures which arerelatively movable to vary from a normal the distance between saidconnections of said link to said pitman arm and said steering means,said link further including valve means interposed between and connectedto said motor and said source for controlling the operation 0) saidmotor, said valve means including relatively movable valve elementsrespectively forming parts of said relatively movable structures andmovable therewith from a neutral position in response to any variationin said distance from said normal to control the operation of saidmotor; and hydraulic means acting 'on said relatively movable structuresand operable by said hydraulic fluid for biasing said relatively movablestructures in such directions as to tend to restore said distance tosaid normal in response to any variation thereof from said normal.

15. A power steering apparatus as defined in claim 14 wherein said valvemeans includes means for maintaining said hydraulic means in constantcommunication with said source.

16. A. power steering apparatus as defined in claim 14 wherein saidhydraulic means includes rings encircling one of said valve elements andengageable with shoulders on said valve elements.

17. A booster for a vehicle having a steered assembly and a pitman arm,a fluid motor connected to said assembly, pump mechanism to supplypressure to said fluid motor to actuate the same, means of communicationbetween said pump mechanism and said fluid motor, a link' connectedbetween said pitman arm and said assembly, a control valve forming apart of said link and comprising a pair of telescopicallyrelated valveelements for controlling the flow between said pump mechanism and saidmotor in response to telescopic adiustment of said elements, and meansto resist telescopic adjustment of said valve elements and changing ofthe length of said link, said means being actuated by fluid pressurefrom said pump mechanism and acting on said valve elements.

18. A steerin booster as defined in claim 1 wherein the means lastdefined includes means constantly urged in one direction by pressurefrom said source and having lost-motion connections with said valveelements.

References Cited in the file of'this patent

